We present an investigation of the quantum confined energy levels in a mid-wave infrared and long-wave infrared InAs/GaSb type II strained-layer superlattice (SLS) photodetector by computing the first derivative of the absorption spectra from 80K to 250K , with respect to the wavelength. Energy levels of both the fundamental transition and two other higher orders are identified for the SLS. The temperature evolution of each of these bands was also characterized by fitting the energy transitions to the Varshni equation, which showed that in general, the higher-energy transitions have a greater change in bandgap with temperature than the lower-energy ones. The transition energies appeared linearly dependent on the InAs layer thickness, and had a weaker dependence on the GaSb layer thickness. A feature that vanished at higher temperatures was also observed, which is due to a GaSb characteristic, rather than the superlattice.

Date Published: 31 May 2012
PDF: 6 pages
Proc. SPIE 8353, Infrared Technology and Applications XXXVIII, 83530X (31 May 2012); doi: 10.1117/12.919616

Published in SPIE Proceedings Vol. 8353:
Infrared Technology and Applications XXXVIII
Bjørn F. Andresen; Gabor F. Fulop; Paul R. Norton, Editor(s)